Trace fossils, found on shells of gastropods, bivalves and scaphopods from Molluscan Clay exposures (Oligocene, Egerian) at Eger (Wind brickyard) and Novaj (Nyárjas Hill) (NE Hungary), were studied.The relative abundance of different types of borings, traces of bioerosion and palaeopathological phenomena indicate micro-environmental differences between the two localities.